1. Field of the Invention
The invention relates to a guide plate for a system for fastening a rail to a substrate on which there is provided, laterally of the railway track, a shoulder which absorbs the forces which are produced when a rail vehicle travels on the rail. The guide plate has in this case an underside which is associated with the substrate and an upper side which is exposed in the installation position, is arranged remote from the underside and on which it is possible to support a spring element provided for applying resiliently elastic holding-down forces to the rail to be fastened.
In addition, the invention relates to a system for fastening a rail to a substrate on which there is provided, laterally of the railway track, a shoulder. The system according to the invention comprises in this case a spring element for exerting an elastic holding-down force on the rail, a guide plate for guiding the spring element and a tensioning element for bracing the spring element against the substrate.
2. Prior Art
In systems of this type, the object of the guide plates is, on the one hand, to absorb the forces occurring when the rail is traveled on and are directed transversely to the rail longitudinal direction and to transmit them to the shoulder which is securely fixed to the substrate. On the other hand, the guide plates serve as a rest for a respective spring element which exerts, when a rail fastening system equipped with the guide plate is fully installed, the required elastic holding-down force on the rail foot.
Guide plates known by the name “angled guide plates”, such as for example that offered by the Applicant under the designation “W14”, have a basic shape which, viewed from above, is rectangular and elongate and on one longitudinal side of which, associated with the rail, a guide surface is designed. When the guide plate is fully installed, this guide surface abuts fully against the rail foot and fixes the position of the rail in the transverse direction. In this case, the known angled guide plate has a through-opening which is oriented roughly centrally, extends from its upper side down to its underside and through which it is possible to pass during installation a fastening screw which braces the guide plate, with the spring element arranged thereon, against the substrate.
In addition to the prior art commented on hereinbefore, DE 41 01 198 C1 describes a guide plate intended for fastening a rail by means of a ω-shaped tensioning clamp. Depressions, in which the central part, which is bent in a U-shaped manner, of the tensioning clamp is positioned after installation, are provided in the known guide plate. In addition, the known angled guide plate has a flute extending parallel to the rail in the installation position. The outwardly leading portions of the tensioning clamp are supported in this flute after installation, longitudinally and transversely to the rail to be fastened in each case.
The known guide plates described hereinbefore presuppose the design of a shoulder in or on the respective substrate, on which shoulder the guide plate rests when installed. Conventionally, this shoulder is formed by a step which is moulded onto the substrate and against which the guide plate rests with its side remote from the rail when installed.
Another possibility of supporting a rail is described in U.S. Pat. No. 4,313,563. In this system for fastening a rail, which is also known by the name “Safelok”, a shoulder piece, which is made from cast iron material, is cast into the fixed substrate which is generally formed from a concrete sleeper. This shoulder piece has, at its portion resting freely on the surface of the fixed substrate, a receptacle, the opening of which is arranged on the side of the step that is remote from the rail to be fastened.
In the Safelok system, a spring clip, which is shaped integrally from flat steel and has a crosspiece from which two spring arms running substantially parallel to each other emanate, engages into the recess of the shoulder. These spring arms are guided, viewed from the side, starting from the crosspiece positioned in the recess of the shoulder piece, in a large arc in the direction of the rail to be fastened, the spring arms ending, when untensioned, in a position arranged below the crosspiece. When installed, the spring arms press in a correspondingly pretensioned manner with their free ends onto the foot of the rail to be fastened, the upper side of which foot is located substantially at the same level as the receptacle of the shoulder.
The advantage of the Safelok system consists in the fact that it can be installed using a specially shaped tool. In practice, it has been found that, under the high loads resulting from heavy-load or high-speed traffic, force and spring excursion losses, as a result of which the spring force is greatly reduced, occur in the spring clips used in these systems within a short period of use. It can also occur that the spring clips are deformed during installation to the extent that they lose the spring properties required for properly holding down the rail. As a consequence of the decreasing spring action, the resistance to sliding-through of the rail foot in a direction directed to transversely to the longitudinal extension of the rail is also reduced.
A further disadvantage of the known the Safelok system, which has a particularly negative effect specifically in high-speed and heavy-load traffic, consists in the fact that in this system the rail is not protected against tilting which can occur, in particular, when high transverse forces occur. Finally, in the known Safelok system, the requirement for maximum possible insulation of the rail in relation to the substrate supporting it may be fulfilled only in a highly complex manner.